Method for distributed interference coordination in a femtocell environment

ABSTRACT

Distributed inter-cell interference coordination in a communications system can include: at one other femtocell system, sending channel quality information of a subordinate device communicating with the other femtocell system to the first femtocell system; receiving the channel quality information of the at least one other femtocell system at the first femtocell system; estimating an influence of a use of a resource on the communications system at the first femtocell system according to the channel quality information received by one or more of the at least one other femtocell system; and determining at the first femtocell system whether to use the resource.

BACKGROUND

A femtocell is a small cellular base station that can be configured tobe used indoors, such as within a home or small business, to provide asignal to a mobile device, such as a mobile phone or portable computerwith a mobile card or modem. The femtocell is configured to tie into aservice provider network broadband connection, such as DSL or cable. Thefemtocell can be configured to support various numbers of mobiledevices; however, current designs usually support 2 to 4 active mobiledevices in a residential setting, and 8 to 16 active mobile devices insmall business settings (i.e., enterprise setting). A femtocell allowsservice providers to extend service coverage indoors, especially whereaccess would otherwise be limited or unavailable. The femtocell can beconfigured for WCDMA, GSM, CDMA2000, TD-SCDMA, WiMAX, and LTE standards.

Femtocells are an alternative way to deliver the benefits offixed-mobile convergence (FMC). The distinction is that most FMCarchitectures require a new (e.g., dual-mode) mobile device which workswith existing unlicensed spectrum home/enterprise wireless accesspoints, while a femtocell-based deployment will work with existingmobile devices, but requires installation of a femtocell access pointthat uses licensed spectrum.

Generally, a femtocell provides coverage on the order of 10s of metersor less, usually about 50 meters to about 30 meters or less. As such, afemtocell environment is typically the size of a residential gateway orsmaller, and the femtocell access point connects to a broadband line.Integrated femtocells can include both a DSL router and femtocell. Whenmobile devices arrive under coverage of the femtocell, they switch overfrom the macrocell (e.g., outdoor) to the femtocell (e.g., indoor)automatically. All communications then automatically go through thefemtocell. When the user leaves the femtocell coverage area, the mobiledevice hands over seamlessly to the macrocell network. Femtocellsrequire specific hardware, so existing WiFi or DSL routers cannot beupgraded to a femtocell.

Some of the benefits that a femtocell can provide for an end-userinclude: so-called “5 bar” coverage when there would otherwise be noexisting signal or poor coverage; it can provide higher mobile datacapacity, which can be important when the end-user makes use of mobiledata on their mobile device; and the femtocell can have a functionalityand interface that is similar to regular HSPA or LTE base stations,except for a few additional functions with a significantly reducedcoverage area.

The placement of a femtocell has a critical effect on the performance ofthe wider network, and this is a key issue to be addressed forsuccessful deployment. The placement of multiple femtocells in closeproximity can impede performance due to the overlap of signal channels,which can cause two femtocells to compete for the same signal channel.Since femtocells can use the same frequency bands, there can be problemswith adjacent femtocells interfering with each other to reducefunctionality rather than improving functionality.

For example, in order to solve the problems of indoor network coverage,an LTE-A network can incorporate a femtocell, such as a Home Node B(HNB) system or a Home e-Node B (HeNB) system. In this example, aplurality of HeNBs can be densely distributed in a network, whichresults in the formation of serious interferences between differentHeNBs in close proximity. The interference can even cause the nodes inthe network to fail to communicate with each other. Uncertainties of thedisposition and on-offs of the HeNBs can lead to high randomness of theinterferences among the HeNBs.

Attempts have been made to reduce the interference between proximalfemtocells. A traditional centralized inter-cell interferencecoordination technology is limited by its flexibility and transmissiondelay, and may not rapidly track changes of the interferences betweenthe femtocells. Also, interactions frequently occur among the proximalfemtocells, and signaling overhead is high. This can result in theinter-cell interference coordination technology of the traditionalcellular network being insufficient for reducing interference betweenproximal femtocells.

SUMMARY

In one embodiment, a method is provided for distributed inter-cellinterference coordination in a communications system including at leasta first femtocell system and at least one other femtocell system. Themethod can include: at one or more other femtocell systems, sendingchannel quality information γ_(i) of a subordinate device communicatingwith the other femtocell system to the first femtocell system; receivingthe channel quality information γ_(i) of the other femtocell system atthe first femtocell system;

estimating an influence of a use of a resource on the communicationssystem at the first femtocell system according to the channel qualityinformation γ_(i) received by one or more of other femtocell systems;and determining at the first femtocell system whether to use theresource.

The first femtocell system can refer to any femtocell system of aplurality of proximal femtocells. As such, each of the proximalfemtocell systems can operate as the first femtocell system. Thus, thefirst femtocell system is not a specific femtocell system, but rather apoint of reference between a plurality of femtocell systems. Eachfemtocell system can include a femtocell device that communicates acrossthe available channels. The femtocell system can include a Home Node B(HNB) system or a Home e-Node B (HeNB) system.

In one embodiment, a communications system for distributed inter-cellinterference coordination can include a first femtocell (e.g., HeNB)system, and one or more other femtocell systems configured to sendchannel quality information γ_(i) of a subordinate device communicatingwith the other femtocell system to the first femtocell system. The firstfemtocell system can be configured to receive the channel qualityinformation γ_(i) of the at least one other femtocell system at thefirst femtocell system. The first femtocell system can then estimate aninfluence of a use of a resource on the communications system at thefirst femtocell system according to the channel quality informationγ_(i) received by one or more of the other femtocell systems. The firstfemtocell system can then determine whether to use the resource.

In one embodiment, the first femtocell system can include a computingunit configured as a femtocell access point device. The computing unitcan be capable of executing a series of executable instructions storedin a tangible medium in order to perform various femtocell protocols.With regard to reducing interference between proximal femtocell systems,the first femtocell system can implement the following steps: receivingchannel quality information γ_(i) of another femtocell system at thefirst femtocell system; estimating an influence of a use of a resourceon the communications system at the first femtocell according to thechannel quality information γ_(i) received by one or more otherfemtocell systems; and determining at the first femtocell whether to usethe resource.

In one embodiment, a method is provided for distributed inter-cellinterference coordination in a first femtocell system (e.g., HeNB). Sucha method can include: receiving, at the first femtocell system, channelquality information γ_(i) of a subordinate device communicating with oneor more other femtocell systems interfering with the first femtocell ina communications network; estimating an influence of a use of a resourceon the communications system according to the channel qualityinformation γ_(i) received from one or more other femtocell systems; anddetermining whether to use the resource.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and following information as well as other features ofthis disclosure will become more fully apparent from the followingdescription and appended claims, taken in conjunction with theaccompanying drawings. Understanding that these drawings depict onlyseveral embodiments in accordance with the disclosure and are,therefore, not to be considered limiting of its scope, the disclosurewill be described with additional specificity and detail through use ofthe accompanying drawings, in which:

FIG. 1 includes a schematic representation of a high level femtocellnetwork architecture;

FIG. 2 includes a schematic representation of a femtocell system;

FIG. 3 includes a schematic representation of a computing system thatcan be used with a femtocell system;

FIG. 4 includes a flow diagram representing an embodiment of a methodfor reducing interference between femtocell systems in a femtocellenvironment;

FIG. 5A includes a flow diagram representing a process that can beimplemented in a method for reducing interference between femtocellsystems in a femtocell environment;

FIG. 5B includes a flow diagram representing an embodiment of a processfor determining whether or not to use a certain carrier wave or adifferent carrier wave;

FIG. 6 includes a flow diagram representing an embodiment of a processfor determining whether or not use of a carrier wave can reduceinterference between femtocell systems in a femtocell environment;

FIG. 7 includes a flow diagram representing an embodiment of a processfor determining whether to use a certain carrier wave or to discard acertain carrier wave in a femtocell environment to reduce interference;

FIG. 8 includes some processes that can be performed during any of themethods for reducing interference in a femtocell environment;

FIG. 9 includes a flow diagram representing a process that can be usedin a method for reducing interference between femtocell systems in afemtocell environment;

FIG. 10 includes a flow diagram representing a process for determiningwhether or not to use a certain carrier wave in a femtocell environment;

FIG. 11 includes a flow diagram representing a process for determiningwhether or not to use a certain resource in a femtocell environment;

FIG. 12 provides a schematic representation of a simple femtocellenvironment,

all arranged in accordance with at least one of the embodimentsdescribed herein, and which arrangement may be modified in accordancewith the disclosure provided herein by one of ordinary skill in the art.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented herein. It will be readily understood that the aspects of thepresent disclosure, as generally described herein, and illustrated inthe figures, can be arranged, substituted, combined, separated, anddesigned in a wide variety of different configurations, all of which areexplicitly contemplated herein.

Due to the significant problems that arise resulting from femtocellnetwork interference, there is a need to provide a distributedinter-cell interference coordination technology. By adopting asuccessful distributed inter-cell interference coordination technologyin the femtocell network, each femtocell system can change resourceusage according to the information obtained from proximal femtocellsystems. The exchange of information between femtocell systems can allowfor changes of in inter-cell interferences to be rapidly, tracked with alow signaling overhead. That is, the distributed inter-cell interferencecoordination technology does not impact the available bandwidth as muchas a centralized technology. The inter-cell interferences can beeffectively reduced by the distributed inter-cell interferencecoordination technology, and the performance (e.g., receivingperformance) of the network can be enhanced.

While femtocell systems are described herein with regard to the advancein communications technology, the 3^(rd) Generation Partnership Project(3GPP) refers to 3G femtocells as Home Node B (HNB) for WCDMA and Homee-Node Bs (HeNB) for LTE. With regard to LTE, a femtocell thereforerefers to a HeNB system. With regard to WCDMA, a femtocell thereforerefers to a HNB. A goal of the 3GPP Long Term Evolution (LTE) program isto develop new technology, new architecture and new methods for LTEsettings and configurations in order to provide improved spectralefficiency, reduced latency, and better utilization of radio resourcesfor faster user experiences and richer applications and services withless cost. As part of these efforts, the 3GPP has introduced the conceptof an in-home HeNB for LTE networks and in-home HNB for wideband codedivision multiple access (WCDMA).

The present technology can be generalized for femtocells that have thecapability of downlink receiving. Also, the present technology can beperformed by implementing an ICIC algorithm, which is useful forfemtocells in close proximity, but may not be useful for communicationplatforms that are located at longer distances with respect to eachother. As such, the technology may not apply to e-Node B (eNB) or otherlarge-scale base station communication platforms that transmit over longdistances.

The technology may also be useful in microcells and picocells, but onlywhen the microcells and picocells operate similarly with the HNBs andNeNB, such as when capable of implementing downlink receiving and/orcapable of implementing the ICIC algorithm. Typically, the range of amicrocell is less than two kilometers wide down to about 200 meters, anda picocell range is about 200 meters to about 100 meters. On the otherhand, femtocells are much smaller, such as on the order of 10 s ofmeters or less, usually about 50 meters to about 30 meters or less.

Generally, the technology is provided for distributed inter-cellinterference coordination in a communications system including at leasta first femtocell system (e.g., first HeNB system) of a first femtocellenvironment and at least one other femtocell system (e.g., second HeNBsystem) of the first femtocell environment or other environment, such asa second femtocell environment. The other femtocell system can be asecond femtocell system, a third femtocell system, and so on. Afemtocell environment can have one or more operational femtocellsystems, and adjacent femtocell environments can overlap within thecommunications system. A femtocell system can include one or moredevices configured together to perform a femtocell function. A femtocellaccess point can include a femtocell system.

In one embodiment, the method can include: at one or more of the otherfemtocell systems (e.g., not the first femtocell system), sendingchannel (e.g., one or more channels) quality information γ_(i) of asubordinate device (e.g., mobile phone or mobile computing device)communicating with at least one of the other femtocell systems to thefirst femtocell system; receiving the channel quality information γ_(i)of one or more of the other femtocell systems at the first femtocellsystem; estimating an influence of a use of a resource on the firstfemtocell system according to the channel quality information γ_(i)received by one or more of the other femtocell systems; and determiningat the first femtocell system whether to use the resource.

FIG. 1 provides a schematic representation of a femtocell environment100 that includes a network 110 that operably couples a femtocellgateway 112 and mobile core network 114 to a home network 116 and to anenterprise network 126 through a LAN/WLAN 125. The home network 116 isshown to have a femtocell access point 120, which is generally referredto herein as a femtocell system. A femtocell system can include one ormore devices that cooperatively operate as a femtocell access point 120.The femtocell system can also be referred to as a femtocell device as itis operably coupled with a broadband network 110. The femtocell accesspoint 120 communicates with a mobile device 122, such as a mobile phone,and with a mobile computer 124 that has mobile network capabilities,such as through a mobile card or mobile USB plugin. In this setup, thereis only one femtocell access point 120 for the home network 116, andthereby there may not be any interference between femtocell accesspoints 120. On the other hand, if the home having the home network 116is in a high density residence area, other homes may have other homenetworks 116 with femtocell access points 120 that may interfere witheach other. The dashed line box of the home network 116 represents thecell coverage area of the femtocell access point 120.

The enterprise network 126 is shown to be operably coupled with thenetwork 110 through a LAN/WLAN 125, which is optional. The enterprisenetwork 126 may be operably coupled directly to the network 110. Theenterprise network 126 is shown to have a first femtocell access point128 a, a second femtocell access point 128 b, and a third femtocellaccess point 128 c; however, any number of femtocell access points maybe present in close proximity. The enterprise network 126 can be asingle business entity or can include multiple businesses in closeproximity, such as in an office building. The first femtocell accesspoint 128 a can be in communication with a first mobile device 130 a anda first mobile computer 132 a. The second femtocell access point 128 bcan be in communication with a second mobile device 130 b and a secondmobile computer 132 b. The third femtocell access point 128 c can be incommunication with a third mobile device 130 c and a third mobilecomputer 132 c. The femtocell access points 128 a,b,c may be exemplifiedby HNB or HeNB systems.

The enterprise network 126 is shown to have a dashed line box, whichrepresents the broad cell coverage area of the femtocell access points128 a,b,c. Each femtocell access point 128 a,b,c has a cell coveragearea represented by the dashed boxes that overlap. This overlap of cellcoverage can create unwanted interference between the differentfemtocell access points 128 a,b,c.

Each femtocell access point 120 can include hardware and softwareconfigured for one or more of the following: protocols covering LTE HeNBand 3G HNB; data and control performance aligned with High Speed PacketAccess (HSPA), HSPA+ and LTE latency and data throughput standards; afemtocell reference application; integrated protocol stacks; and anyother femtocell functionality, such as those known and/or describedherein or developed.

FIG. 2 provides a schematic representation of a femtocell access point220 configured as a HeNB system. The femtocell access point 220 can havesome of the following: a femtocell management application module 222; afemtocell reference application module 224; an inter-cell radio resourcemanagement (RRM) module 226; a resource block (RB) control module 228; aconnection mobility module 230; a radio admission module 232; amonitoring center performance (MCP) module 234; a dynamic resourceallocation (DRA) module 236; a radio resource controller (RRC) module238; a packet data convergence protocol (PDCP) module 240; a radio linkcontrol (RLC) module 242; a silicon convergence layer (SCL) module 244;a physical layer (PHY) module 246; an internet protocol security (IPSEC)module 248; a X2 application protocol (X2AP) 250; S1 applicationprotocol (S1AP) module 252; an enhanced general packet radio service(GPRS) tunneling protocol (eGTP) module 254; and stream controlledtransmission protocol (SCTP) module 256. The aforementioned componentsof the femtocell access point 220 are well known to one of ordinaryskill in the art. The femtocell access point 220 configured asillustrated and described in connection to FIG. 2 can implement themethods described herein in order to reduce interference betweenadjacent femtocells. The illustrated femtocell access point 220 can be aHeNB system as configured.

FIG. 3 provides a schematic representation of a computing system 300that can be implemented as a femtocell system in accordance with thedisclosure provided herein. The computing system 300 of FIG. 3 isdescribed in more detail below.

FIG. 4 provides a flow diagram of a method 400 for reducing inter-cellfemtocell interference. The method 400 can be implemented by a HeNBfemtocell access point 220 of FIG. 2 as well as an HNB having downlinkreceiving capability and being configured to implement an ICICalgorithm. The method 400 may be implanted in a femtocell environment100 of FIG. 1. Generally, the method 400 can be used for distributedinter-cell interference coordination in a communications systemincluding at least a first femtocell system and at least one otherfemtocell system. The method 400 can include providing a femtocellenvironment having two or more femtocell systems (“PROVIDE A FEMTOCELLENVIRONMENT,” block 410), which can be located within an interferencearea. The femtocell systems can be identified by a first femtocellsystem and at least one other femtocell system (“IDENTIFY FEMTOCELLS INENVIRONMENT,” block 412), which may or may not have interference betweeneach other. The other femtocell systems can then obtain channel qualityinformation □_(i) of a subordinate device, such as a mobile phone, thatis communicating with one of the other femtocell systems, such as thefirst femtocell system (“OBTAIN CHANNEL QUALITY INFORMATION □_(i),”block 414). The other femtocell system can then transmit the obtainedchannel quality information □_(i) of the subordinate device to the firstfemtocell system (“TRANSMIT CHANNEL QUALITY INFORMATION □_(i), ” block416). The first femtocell system can then receive the channel qualityinformation □_(i) regarding the subordinate device communication withthe other femtocell system (“RECEIVE CHANNEL QUALITY INFORMATION □_(i),”block 418). Once the channel quality information □_(i) regarding thecommunication between the subordinate device and the other femtocellsystem is received, the first femtocell system can then estimate aninfluence of a use of a resource on the communications system accordingto the channel quality information □_(i) provided by the other femtocellsystem (“ESTIMATE INFLUENCE OF USE OF RESOURCE ON COMMUNICATIONSSYSTEM,” block 420). The first femtocell includes hardware and/orsoftware that can be configured to process the channel qualityinformation □_(i) to obtain useful information and make appropriatedeterminations. The first femtocell system can use the availableinformation and determine whether to use the resource, such as aparticular channel being used by the subordinate device and the otherfemtocell system (“DETERMINE WHETHER TO USE A RESOURCE,” block 422).

During the method 400 of FIG. 4, other processes and functions can beimplemented by the femtocell systems of the femtocell environment. Assuch, the various femtocell systems can store the channel qualityinformation □_(i) on a data storage medium (“STORE QUALITY INFORMATION,”block 424). For example, the first femtocell system can store thechannel quality information □_(i) on a computing system-readable medium.The dashed line box of FIG. 4 illustrates that the other processes maybe optional in various configurations, and may be performed at varioustimes through the method 400, and thereby the other processes are notlinked via the flow chart.

The channel quality information can be obtained for each carrier wave ofthe femtocell environment (“OBTAINING CARRIER WAVE QUALITY INFORMATION,”block 426). The channel quality information □_(i) for each carrier wavek can then be broadcast from one femtocell system to another femtocellsystem, such as a proximal femtocell system in the femtocell environment(“BROADCAST CARRIER WAVE QUALITY INFORMATION,” block 428). The abilityof the femtocell systems to pass information between each other in orderto reduce interference is more effective than a central system thatdirectly controls each femtocell system. The distributed communicationallows the femtocell systems to adjust their carrier waves k in use onthe fly. The method 400 for distributed inter-cell interferencecoordination can include the following processes performed by thefemtocells: at one or more of the other femtocell systems, sendingchannel quality information □_(i) of a subordinate device communicatingwith the other femtocell system to the first femtocell system; receivingthe channel quality information □_(i) of the other femtocell system atthe first femtocell system; estimating an influence of a use of aresource on the communications system at the first femtocell systemaccording to the channel quality information □_(i) received by one ormore of the other femtocell systems; and determining at the firstfemtocell system whether to use the resource.

One skilled in the art will appreciate that, for this and otherprocesses and methods disclosed herein, the functions performed in theprocesses and methods may be implemented in differing order.Furthermore, the outlined steps and operations are only provided asexamples, and some of the steps and operations may be optional, combinedinto fewer steps and operations, or expanded into additional steps andoperations, without detracting from the essence of the disclosedembodiments. Of course, all of the methods described herein can becombined, and the individual processes can be separated and alternatelycombined in order to reduce inter-cell interference in a femtocellenvironment.

FIG. 5A provides a flow diagram of a method 500 a for using a fadingmatrix F in order to improve interference between femtocell systems. Themethod 500 a can include the first femtocell system obtaining a fadingmatrix F of the first femtocell channels between the first femtocellsystem and one other femtocell system, and/or the other femtocell systemdetermining its fading matrix F (“OBTAIN FADING MATRIX F,” block 510 a).The fading matrix F can be obtained by the first femtocell systemobtaining a reference signal received power (RSRP) from at least one ofthe other femtocell systems (“OBTAIN RSRP,” block 512 a). The RSRP ismeasured by a different femtocell system in order to determine how thesignal of the first femtocell system fades as it reaches out toward theother femtocell system, and vice versa. The fading matrix F from thefirst femtocell system to another femtocell system, such asfemtocell_(i), is represented by F_(0,i), where F₀ is the fading fromthe first femtocell system and F_(i) is the fading from the otherfemtocell system. The fading matrix F can be obtained from fadingvalues.

Once the fading matrix F is obtained, the femtocell system can thendetermine an interference correlative matrix D that corresponds with thefading values of the fading matrix F relative to a predeterminedthreshold value Γ_(T) (“DETERMINE INTERFERENCE CORRELATIVE MATRIX D,”block 514 a). The interference correlative matrix D can be determinedby, if F_(0,i) is less than a predetermined threshold value Γ_(F) (e.g.,Γ_(F) is the fading value threshold for the transmitting femtocell F),then the interference correlative matrix D from the first femtocellsystem to the other femtocell_(i) system, D_(0,i), is equal to 1 (i.e.,if F_(0,i)<Γ_(F), then D_(0,i)=1). Each femtocell system broadcastschannel quality information □_(i) of the subordinate devices served bythe particular femtocell system for each carrier wave k in a certainperiod of time. Each femtocell system records the information related tothe fading matrix F and interference correlative matrix D (“RECORDFADING MATRIX F INFORMATION,” Block 518 a; “RECORD INTERFERENCECORRELATIVE MATRIX D,” Block 516 a). Each femtocell system can performthis process to obtain initialization information for each channel.

The correlative matrix D reflects the interference relationship betweendifferent femtocell systems. D_(ij)=1 indicates that the fading betweenfemtocell i and femtocell j is smaller than a certain threshold, thusthe two different femtocells probably interfere with each other. Onlyfemtocells interfering with each other need to negotiate the usage ofcarriers because the carrier usage of other femtocells with nointerference does not affect the current femtocell.

The femtocell systems can each perform a set of processes in regard tothe initialization information obtained from the method 500 a. Thefemtocell systems can determine the order of the processes by passinginstructions between them by an arbitrary process of self-optimization.Part of the process can involve the throughput of the femtocell system,which is represented by T, where the throughput T for the firstfemtocell can be T₀. Correspondingly, the throughput of the firstfemtocell system of carrier wave k can be represented by T₀ ^(k).

FIG. 5B provides a flow diagram of a method 500 b of estimating theinfluence of a use of a resource on the communications system. As such,the method 500 b can include estimating the throughput T₀ ^(k) of thefirst femtocell system which can be obtained on a carrier wave k(“ESTIMATE THROUGHPUT T₀ ^(k),” (block 510 b). The first femtocellsystem can then base on the RSRP received from other femtocell systemsto identify a second femtocell system with the strongest interferencewith the first femtocell system and the carrier wave k with thestrongest interference between the first femtocell system and the secondfemtocell system (“IDENTIFY STRONGEST INTERFERENCE FOR k,” block 512 b).The first femtocell system can then determine whether or not T₀ ^(k)<Γ_(T), where Γ_(T) corresponds to the predetermined threshold value(“DETERMINE WHETHER T₀ ^(k)<Γ_(T). FOR k,” block 514 b). If thethroughput is more than the threshold Γ_(T) (“NO,” block 516 b), thefirst femtocell system identifies a second carrier wave k₂ then goesback to block 510 b and estimates a throughput for the second carrierwave k₂ (“DETERMINE k2,” block 520 b). Note that the first carrier wavebecomes k₁. When the femtocell system cannot use the carrier wave k, thefirst femtocell system negotiates with the second femtocell system aboutusing a carrier wave k2, which is at least substantially orthogonal tok₁. If the throughput T₀ ^(k) is less than the threshold (“YES,” block518 b), the first femtocell system can use the carrier wave k₁ (“USECARRIER WAVE k,” block 522 b).

Accordingly, when the throughput T₀ ^(k) is less than the thresholdΓ_(T), then the first femtocell system can negotiation with the otherfemtocell system in order to determine a carrier wave k to use. Thefirst femtocell system can negotiate with the other femtocell systemhaving the strongest interference regarding the use of one or more wavesk. The negotiation can include the first femtocell system using acarrier wave k that is at least substantially orthogonal to the carrierwave k used by the other femtocell system with the strongestinterference. As such, the throughput T₀ ^(k) can increase for the firstfemtocell system to ensure fairness of the femtocell environment withregard to carrier waves used between proximal femtocell systems. Also,the first femtocell system can observe all carrier waves in a randomorder or in a predetermined order. When the carrier waves being used bythe first femtocell system are observed, the first femtocell system cancalculate the throughput T₀ ^(k) of a carrier wave k. For otherfemtocell systems, the first femtocell system can calculate thethroughput T₀ ^(k) of the carrier wave k which can be obtained on thecurrent carrier wave k.

FIG. 6 provides a flow diagram of another embodiment of a method 600 ofestimating the influence of a use of a resource on the communicationssystem. The method 600 can include determining which carrier waves ofthe first femtocell system are being used by the first femtocell system(“DETERMINING CARRIER WAVES,” block 610). This determination can beperformed by each of the femtocell systems in the femtocell environmentas the point of reference as to which femtocell system is the firstfemtocell system in the estimation of influence. The first femtocellsystem can calculate the throughput T₀ ^(k) of the carrier wave k foreach of the possible carrier waves k of the femtocell environment(“CALCULATE THROUGHPUT T₀ ^(k) OF THE CARRIER WAVE k,” block 612). Thethroughput T₀ ^(k) of the carrier wave k can be related to andcorresponding with the decrement of the throughput for the firstfemtocell system if the first femtocell system discards the carrier wavek (“DETERMINE THROUGHPUT T₀ ^(k) WITH DECREMENT OF THROUGHPUT T₀ ^(k) IFCARRIER WAVE k IS DISCARDED,” BLOCK 614). However, the throughput T₀^(k) of the carrier wave k can automatically correspond with thedecrement of throughput T₀ ^(k) and no actual comparison process mayneed to be performed. The decrement of throughput T₀ ^(k) can bedetermined by the first femtocell system as the first femtocell systemmay be actively attempting to optimize interference with anotherfemtocell system, such as the femtocell_(i) system. The first femtocellcan then estimate the increment of a throughput ΔT_(i) of femtocell_(i),after the first femtocell system discards the carrier wave k (“ESTIMATEINCREMENT OF A THROUGHPUT ΔT_(i) OF FEMTOCELL_(i),” block 616). Theestimation of the a throughput ΔT_(i) of Femtocell_(i) can be from ahypothetical scenario or the first femtocell system can actually discardthe carrier wave k (“DISCARD CARRIER WAVE k,” block 618). Thefemtocell_(i) can correspond with one or more of any other femtocellsystem in the femtocell environment (“CORRESPOND FEMTOCELL_(i) WITHANOTHER FEMTOCELL,” block 620). The femtocell_(i) can correspond withone or more other femtocell systems of the femtocell environmentrelative to the first femtocell system. The femtocell_(i) system cancorrespond with at least one other femtocell systems in a set I of theother femtocell systems. The femtocell_(i) system can correspond withother femtocell systems in a set I of the other femtocell systems, wherethe fading value is less than the predetermined threshold value Γ_(T).

The method 600 can include: for each of the carrier waves being used bythe first femtocell system, the first femtocell system calculates thethroughput T₀ ^(k) of the carrier wave k corresponding what thedecrement of the throughput will be on the first femtocell system if thefirst femtocell system discards the carrier wave k, and the firstfemtocell system can estimate the increment of a throughput ΔT_(i) offemtocell_(i), system after the first femtocell system discards thecarrier wave k, where i corresponds to one or more of the at least oneother femtocell systems in a set I of the other femtocell systems wherefading value is less than the predetermined threshold value Γ_(T).

Accordingly, the first femtocell can calculate the throughput T₀ ^(k) beobtained on the current carrier wave k, which can be the decrement ofthe throughput of the femtocell environment when the first femtocelldiscards the carrier wave k. Also, the first femtocell system canestimate the increment of the throughput ΔT_(i) of another femtocell_(i)system after the carrier wave k is discarded.(iε1, I={j|D _(0,i)=1})

FIG. 7 provides a flow diagram of an embodiment of a method 700 ofdetermining whether to use a resource. The method 700 can be conductedat the first femtocell system. The method 700 can include discarding thecarrier wave k under a first condition or continuing to use the carrierwave k under a second condition. Accordingly, the first femtocell systemcan determine whether or not use of the carrier wave k satisfies acondition (“DETERMINE IF USE OF CARRIER WAVE k SATISFIES CONDITION,”block 710). The first femtocell can define the condition with Equation(1) as follows (“DEFINE CONDITION,” block 712):

$\begin{matrix}{T_{0}^{k} > {\sum\limits_{i \in I}^{\;}\;{\Delta\; T_{i}}}} & (1)\end{matrix}$

The first femtocell system can then make a decision based on whether theuse of the carrier wave k satisfies the condition or not (“MAKE DECISIONIF SATISFIES CONDITION,” block 714). If the condition is satisfied(“CONDITION SATISFIED,” block 716), the first femtocell system candiscard the carrier wave k (“DISCARD CARRIER WAVE k,” block 718). If thecondition is not satisfied (“CONDITION NOT SATISFIED,” block 720), thefirst femtocell can continue to use the carrier wave k (“USE CARRIERWAVE k,” block 722). However, the equation can have the inequality inthe other direction such that the throughput T₀ ^(k) is less thanincrement of throughput ΔT_(i), and then the opposite decision will bemade regarding whether or not to use the carrier wave k or discard thecarrier wave k.

Accordingly, the method 700 can include: determining at the firstfemtocell system whether to use the resource upon satisfaction ornon-satisfaction of Equation (1). The first femtocell system can discardthe carrier wave k if T₀ ^(k) and ΔT_(i) satisfy the Equation (1). Onthe other hand, the first femtocell can continue to use the carrier wavek if T₀ ^(k) and ΔT_(i) do not satisfy the Equation (1).

The femtocell environment can calculate values through the firstfemtocell system making the calculation or any other femtocell systemmaking the calculation, and the femtocell systems can provide theinformation between each other. If the throughput T₀ ^(k) is greaterthan the increment ΔT_(i), then the first femtocell system can discardthe carrier wave k. If the throughput T₀ ^(k) is less than the incrementΔT_(i), then the first femtocell system can use the carrier wave k. Withregard to Equation (1), the femtocell environment can ensure that nodecrease of the whole throughput of the femtocell environment occurswhen the first femtocell system discards the carrier wave k. This canallow the femtocell environment to have overall improved performance.The process can be performed at each femtocell system.

The estimation of the throughput T₀ ^(k) could include variousprocesses. The distances between the femtocell systems having stronginterference with each other may be relatively small, so that theinterferences with them are similar to each other. The interferencessuffered by another femtocell system can be approximated to theinterference I₀ suffered by the first femtocell system. Also, thechannel quality γ_(i)′ of another femtocell system when the firstfemtocell system discards the current carrier wave k can be estimatedaccording to the channel quality information □_(i) of the subordinatedevice served by the other femtocell system. The channel qualityinformation □_(i) can be obtained during initialization. The fadingvalue F_(0,i) between the first femtocell system (e.g., femtocell₀) andanother femtocell system (e.g., femtocell_(i)) and the transmissionpower P₀ of the first femtocell system can be estimated or determined,and which can be used during the process.

FIG. 8 provides a flow diagram of an embodiment of a method 800 ofestimating an increment of the throughput ΔT_(i) of a femtocell system(e.g., femtocell_(i)) other than the first femtocell system. The firstfemtocell system or the other femtocell system can perform theestimation. As such, the method 800 can include approximating aninterference I_(i) of each of the other femtocell_(i) systems in the setI as being equal to an interference I₀ of the first femtocell system(“APPROXIMATING INTERFERENCE I_(i),” block 810). The approximating canbe performed by the first femtocell system, or it can be done by anotherfemtocell system and the approximation can be shared. The method 800 caninclude estimating a channel quality □_(i) using channel qualityinformation □_(i) received at the first femtocell system, the fadingstatus F_(0,i) between the first femtocell system and each of the atleast one other femtocell_(i) systems in the set I, and a transmissionpower P₀ of the first femtocell system (“ESTIMATE CHANNEL QUALITY□_(i),” block 812). Also, the method 800 can include determining afading status F_(0,i) between the first femtocell system and each of theat least one other femtocell_(i) systems in the set I (“DETERMINE FADINGSTATUS BETWEEN FEMTOCELL SYSTEMS,” block 814). Also, the fading statusF_(0,i) can be determined between the first femtocell system and I_(i)of each of the at least one other femtocell_(i) systems in the set I.The method 800 can include determining a transmission power P₀ of thefirst femtocell system (“DETERMINE A TRANSMISSION POWER P₀,” block 816).The foregoing estimations of method 800 can be performed according tothe following equations, Equation (2), Equation (3), and Equation (4):

$\begin{matrix}{\gamma_{i} = {\frac{P_{i}}{I_{i} + N} \approx \frac{P_{i}^{\prime}}{I_{0} + N}}} & (2) \\{P_{i}^{\prime} \approx {\gamma_{i} \times \left( {I_{0} + N} \right)}} & (3) \\{\gamma_{i}^{\prime} = \frac{P_{i}}{I_{0} - \left( {P_{0} - F_{0,i}} \right) + N}} & (4)\end{matrix}$

In the foregoing equations, the parameters are as follows: P_(i) istransmission power of femtocell_(i), I_(i) is interference powerreceived by femtocell_(i), P_(i) ^(i) is an estimation of thetransmission power of femtocell_(i) by the first femtocell system, and Nis noise power. The first femtocell system can calculate the throughputincrement □T_(i) when it discard the carrier wave k, by□T_(i)=T_(i)′−T_(i). The parameters can be defined, estimated, ordetermined.

FIG. 9 provides a flow diagram of an embodiment of a method 900 ofestimating the influence of a use of a resource on the communicationssystem in the femtocell environment. The one of the femtocell systemscan calculate the throughput of the carrier wave k corresponding to theincrement □T_(i) of the throughput in the femtocell environment when thefirst femtocell system uses the carrier wave k (“CALCULATE THROUGHPUT T₀^(k) OF USED CARRIER WAVE CORRESPONDING TO THROUGHPUT INCREMENT □T_(i),”block 910). As such, for each of the carrier waves not being used by thefirst femtocell system, the first femtocell can calculate the throughputT₀ ^(k) of the carrier wave k corresponding to the increment of thethroughput □T_(i) on the communication system when the first femtocellsystem uses the carrier wave k. The first femtocell system can estimatethe increment of the throughput □T_(i) of femtocell_(i) after the firstfemtocell discards the carrier wave k (“ESTIMATE THROUGHPUT INCREMENT□T_(i) OF FEMTOCELL AFTER DISCARD CARRIER WAVE k,” block 912).Accordingly, i corresponds to each of the at least one other femtocellsystems in a set I of the other femtocell systems where fading value isless than the predetermined threshold value Γ_(T).

FIG. 10 provides a flow diagram of an embodiment of a method 1000 ofdetermining whether to use a resource. This method 1000 can be performedby the femtocell system determining whether or not to use a resource,such as the first femtocell system. A condition can be defined in orderto use as a basis to determine whether or not to use a resource(“DETERMINE CONDITION,” block 1010). The method 1000 can then determineif the condition is satisfied (“DETERMINE IF CONDITION SATISFIED,” block1012). The method 1000 can include using the carrier wave k at the firstfemtocell system if T₀ ^(k) and ΔT_(i) satisfy the Equation (5) (“USINGCARRIER WAVE k IF CONDITION SATISFIED,” block 1014), where Equation (5)can be the condition:

$\begin{matrix}{\frac{\Delta\; T_{i}}{T_{i}} < \frac{T_{0}^{k}}{T_{0} \times {I_{0}}}} & (5)\end{matrix}$

The parameters can include where |I₀| is the number of elements in theset I of the other femtocell systems where fading value is less than thepredetermined threshold value. Alternatively, when the condition is notsatisfied, the first femtocell system may not use the carrier wave k(“DO NOT USE CARRIER WAVE k IF CONDITION NOT SATISFIED,” block 1016).For example, this can include not using the carrier wave k if T₀ ^(k)and ΔT_(i) do not satisfy the Equation (5).

FIG. 11 provides a flow diagram of an embodiment of a method 1100 ofdistributed inter-cell interference coordination in a femtocell systemthat is performed at the first femtocell system. The method 1100 caninclude the first femtocell system receiving channel quality information□_(i) of a subordinate device communicating with at least one otherfemtocell system interfering with the first femtocell in acommunications network (“RECEIVING CHANNEL QUALITY INFORMATION □_(i),”block 1110). The first femtocell system can then estimate an influenceof a use of a resource on the communications system according to thechannel quality information □_(i) received by each of the at least oneother femtocell system (“ESTIMATE AN INFLUENCE OF A USE OF A RESOURCE,”block 1112). The first femtocell system can then determine whether ornot to use the resource based on the channel quality information □_(i)(“DETERMINE WHETHER TO USE RESOURCE,” block 1114). The method 1100 mayalso optionally include storing the channel quality information □_(i) ofthe at least one other femtocell system as described in connection toFIG. 4. Accordingly, any of the processes of any of the blocks of any ofthe flow diagrams of any of the figures can be used in any of the othermethod, such as this method, in order to facility reduction ofinterference in a femtocell environment. Also, any process or stepdescribed herein can be included in any of the methods described hereinand/or illustrated as flow diagrams in the figures.

In one embodiment, the first femtocell system can receive channelquality information □_(i) of a subordinate device by receiving abroadcast of the channel quality information □_(i) of each carrier wavek from one or more other femtocell systems in a certain time period. Thefirst femtocell device can then obtain a fading matrix F of fadingvalues between the first femtocell system and the other femtocellsystem, and determine an interference correlative matrix D correspondingto the fading matrix relative to a predetermined threshold value Γ_(T).

In one embodiment, the first femtocell system can estimate thethroughput T₀ ^(k) of the first femtocell system which can be obtainedon a carrier wave k.

In one embodiment, the first femtocell system can estimate the influenceof a use of a resource on the communications system. This can includeusing the interference correlative matrix D to identify a secondfemtocell system with the strongest interference with the firstfemtocell system and the carrier wave k1 with the strongest interferencebetween the first femtocell system and the second femtocell system. IfT₀ ^(k)<Γ_(T) is not correct, where Γ_(T) corresponds to thepredetermined threshold value, then the first femtocell systemnegotiates with the second femtocell system about using a carrier wavek2, which is at least substantially orthogonal to k1. If T₀k<Γ_(T) iscorrect, then the first femtocell system negotiates with the secondfemtocell system about using a carrier wave k1.

In one embodiment, the first femtocell system can initiate an estimateof the influence of a use of a resource on the communications system bydetermining which carrier waves of the first femtocell system are beingused by the first femtocell system. The first femtocell can then: foreach of the carrier waves being used by the first femtocell system;calculate the throughput T₀ ^(k) of the carrier wave k correspondingwhat the decrement of the throughput will be on the first femtocellsystem if the first femtocell system discards the carrier wave k, andestimate the increment of the throughput ΔT_(i) of femtocell_(i), afterthe first femtocell system discards the carrier wave k, where icorresponds to each of the at least one other femtocell systems in a setI of the other femtocell systems where fading value is less than thepredetermined threshold value Γ_(T).

In one embodiment, the first femtocell system can discard the carrierwave k at the first femtocell system if T₀ ^(k) and ΔT_(i) satisfy theEquation (1), or continue to use the carrier wave k if T₀ ^(k) andΔT_(i) do not satisfy the Equation (1). Also, the Equation (1) can berearranged to have the opposite inequality and then this embodiment isreversed in terms of whether or not to discard the carrier wave orcontinue to use the carrier wave.

In one embodiment, the first femtocell system can estimate the incrementof the throughput ΔT_(i) of femtocell_(i), after the first femtocellsystem discards the carrier wave. This process can include:approximating an interference I_(i) of each of the at least one otherfemtocell_(i) systems in the set I as being equal to an interference I₀of the first femtocell system; estimating channel quality γ_(i)′ usingchannel quality information γ_(i) received at the first femtocellsystem, a fading status F_(0,i) between the first femtocell system andeach of the at least one other femtocell_(i) systems in the set I, afading status between the first femtocell system and I_(i) of each ofthe at least one other femtocell_(i) systems in the set I; and/or atransmission power P₀ of the first femtocell according to Equation (2),Equation (3), and Equation (4), with the parameters as described herein.

In one embodiment, for each of the carrier waves not being used by thefirst femtocell system, the first femtocell system can calculate thethroughput T₀ ^(k) of the carrier wave k corresponding to the incrementof the throughput ΔT_(i) on the communication system when the firstfemtocell system uses the carrier wave k. The first femtocell can thenestimate the increment of the throughput ΔT_(i) of femtocell_(i), afterthe first femtocell system discards the carrier wave k, where icorresponds to each of the at least one other femtocell systems in a setI of the other femtocell systems where fading value is less than thepredetermined threshold value Γ_(T).

In one embodiment, the first femtocell system can use the carrier wave kat the first femtocell system if T₀ ^(k) and ΔT_(i) satisfy the Equation(5), where |I₀| is the number of elements in the set I of the otherfemtocell systems where fading value is less than the predeterminedthreshold value Γ_(T). On the other hand, the first femtocell system maynot use the carrier wave k if T₀ ^(k) and ΔT_(i) do not satisfy theEquation (5).

In one embodiment, the first femtocell system can estimate a channelquality γ_(i)′ using channel quality information γ_(i) received at thefirst femtocell system, using a fading value F_(0,i) between the firstfemtocell system and each of the at least one other femtocell_(i)systems in the set I, using a fading status between the first femtocelland I_(i) of each of the at least one other femtocell_(i) systems in theset I, and/or using a transmission power P₀ of the first femtocellsystem according to Equation (2), Equation (3), and Equation (4).

The femtocell systems described herein and methods of operation can beimplemented by a HeNB system. Such a HeNB system can be configured tohave the ability for downlink receiving of data. Also, the HeNB canobtain the fading information directly by measurements at the HeNB. EachHeNB can broadcast the channel quality information of a mobile device,such as a subordinate mobile device, served by the present HeNB. TheHeNB can use interfaces between proximal HeNBs to implement an ICICalgorithm. The proximal HeNBs can make reasonable assessments aboutinterference experienced by one HeNB that is interfering with anotherHeNB. The proximal HeNBs work together to reduce interference.

The methods described herein to reduce interference in a femtocellenvironment can be implemented by a communications system. As such, FIG.12 illustrates such a communications system 1200. The minimumcommunications system 1200 can include a first femtocell system 1202 andat least one other femtocell system 1204. The dashed line box shows thefirst femtocell system 1202 and the other femtocell system 1204 are inthe same femtocell environment and can have interference. The otherfemtocell system can be configured to send channel quality information□_(i) of a subordinate device communicating with the other femtocellsystem to the first femtocell system. The first femtocell system can beconfigured to receive the channel quality information □_(i) of the atleast one other femtocell system. The first femtocell system can also beconfigured to estimate an influence of a use of a resource on thecommunications system according to the channel quality information □_(i)received by each of the at least one other femtocell system. The firstfemtocell system can then determine whether to use the resource. Thefirst femtocell can be further configured to store the channel qualityinformation □_(i) of the at least one other femtocell system of thefirst femtocell system. The various femtocell systems can be configuredto send channel quality information □_(i) of a subordinate device bybroadcasting the channel quality information □_(i) of each carrier wavek of the in a certain time period. Any of the femtocells can broadcastsuch information to the other proximal femtocells in the femtocellenvironment.

In one embodiment, the first femtocell can be configured to: obtain afading matrix F of fading values between the first femtocell system andat least on other femtocell system. The first femtocell system can thendetermine an interference correlative matrix D at the first femtocellsystem corresponding to a fading matrix F determined by facing valuesrelative to a predetermined threshold value Γ_(T). The first femtocellsystem can be configured to estimate the influence of a use of aresource on the communications system comprises estimating thethroughput T₀ ^(k) of the first femtocell system which can be obtainedon a carrier wave k.

In one embodiment, the first femtocell system can be configured toestimate the influence of a use of a resource on the communicationssystem. Such a configuration can facilitate the ability to use theinterference correlative matrix D to identify a second femtocell systemwith a strongest interference with the first femtocell system and thecarrier wave k1 with the strongest interference between the firstfemtocell system and the second femtocell system. If not T₀ ^(k)<Γ_(T),where Γ_(T) corresponds to the predetermined threshold value, the firstfemtocell system negotiates with the second femtocell system about usinga carrier wave k2, which is at least substantially orthogonal to k1. IfT₀ ^(k)<Γ_(T), the first femtocell system negotiates with the secondfemtocell system about using a carrier wave k1.

In one embodiment, the first femtocell system can be configured toestimate the influence of a use of a resource on the communicationssystem. This can include being configured to determine which carrierwaves of the first femtocell system are being used by the firstfemtocell system. The first femtocell system can be configured toestimate the influence of a use of a resource on the communicationssystem by: for each of the carrier waves being used by the firstfemtocell system, the first femtocell system calculates the throughputT₀ ^(k) of the carrier wave k corresponding what the decrement of thethroughput will be on the first femtocell system if the first femtocellsystem discards the carrier wave k; and estimating the increment of thethroughput ΔT_(i) of femtocell_(i), after the first femtocell systemdiscards the carrier wave k, where i corresponds to each of the at leastone other femtocell systems in a set I of the other femtocell systemswhere fading value is less than the predetermined threshold value Γ_(T).

In one embodiment, the first femtocell system can be configured todetermine whether to use the resource by: discarding the carrier wave kat the first femtocell system if T₀ ^(k) and ΔT_(i) satisfy the Equation(1), or continuing to use the carrier wave k if T₀ ^(k) and ΔT_(i) donot satisfy the Equation (1).

In one embodiment, the first femtocell system can be configured toestimate the increment of the throughput ΔT_(i) of femtocell_(i), afterthe first femtocell system discards the carrier wave, which can include:approximating an interference I_(i) of each of the other femtocell_(i)systems in the set I as being equal to an interference I₀ of the firstfemtocell system; and estimating channel quality γ_(i)′ using channelquality information γ_(i) received at the first femtocell system, afading status F_(0,i) between the first femtocell system and each of theother femtocell_(i) systems in the set 1, a fading status F_(0,1)between the first femtocell system and I_(i) of each of the at least oneother femtocell_(i) systems in the set I, and a transmission power P₀ ofthe first femtocell system. The estimations can be performed accordingto Equation (2), Equation (3), and Equation (4), defined herein. Assuch, the first femtocell system can be configured to determine thefollowing: P_(i) being transmission power of femtocell_(i); I_(i) beingthe interference power received by femtocell_(i); P_(i)′ being anestimation of the transmission power of femtocell_(i) by the firstfemtocell system; and N is noise power.

In one embodiment, the first femtocell system can be configured toestimate the influence of a use of a resource on the communicationssystem. Such a configuration can include: for each of the carrier wavesnot being used by the first femtocell system, calculating the throughputT₀ ^(k) of the carrier wave k corresponding to the increment of thethroughput ΔT_(i) on the communication system when the first femtocellsystem uses the carrier wave k. It can also include estimating theincrement of the throughput ΔT_(i) of femtocell_(i), after the firstfemtocell system discards the carrier wave k, where i corresponds toeach of the at least one other femtocell systems in a set I of the otherfemtocell systems where fading value is less than the predeterminedthreshold value Γ_(T).

In one embodiment, the first femtocell system can determine whether touse the resource, which can include: using the carrier wave k at thefirst femtocell system if T₀ ^(k) and ΔT_(i) satisfy the Equation (5),where |I₀| is the number of elements in the set I of the other femtocellsystems where fading value is less than the predetermined thresholdvalue Γ_(T); or not using the carrier wave k if T₀ ^(k) and ΔT_(i) donot satisfy the Equation (5).

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its spirit and scope, as will be apparentto those skilled in the art. Functionally equivalent methods andapparatuses within the scope of the disclosure, in addition to thoseenumerated herein, will be apparent to those skilled in the art from theforegoing descriptions. Such modifications and variations are intendedto fall within the scope of the appended claims. The present disclosureis to be limited only by the terms of the appended claims, along withthe full scope of equivalents to which such claims are entitled. It isalso to be understood that the terminology used herein is for thepurpose of describing particular embodiments only, and is not intendedto be limiting.

In an illustrative embodiment, any of the operations, processes, etc.described herein can be implemented as computer-readable instructionsstored on a computer-readable medium. The computer-readable instructionscan be executed by a processor of a mobile unit, a network element,and/or any other computing device.

There is little distinction left between hardware and softwareimplementations of aspects of systems; the use of hardware or softwareis generally (but not always, in that in certain contexts the choicebetween hardware and software can become significant) a design choicerepresenting cost vs. efficiency tradeoffs. There are various vehiclesby which processes and/or systems and/or other technologies describedherein can be effected (e.g., hardware, software, and/or firmware), andthat the preferred vehicle will vary with the context in which theprocesses and/or systems and/or other technologies are deployed. Forexample, if an implementer determines that speed and accuracy areparamount, the implementer may opt for a mainly hardware and/or firmwarevehicle; if flexibility is paramount, the implementer may opt for amainly software implementation; or, yet again alternatively, theimplementer may opt for some combination of hardware, software, and/orfirmware. The modules recited herein can include hardware and/orsoftware.

The foregoing detailed description has set forth various embodiments ofthe processes via the use of block diagrams, flowcharts, and/orexamples. Insofar as such block diagrams, flowcharts, and/or examplescontain one or more functions and/or operations, it will be understoodby those within the art that each function and/or operation within suchblock diagrams, flowcharts, or examples can be implemented, individuallyand/or collectively, by a wide range of hardware, software, firmware, orvirtually any combination thereof. In one embodiment, several portionsof the subject matter described herein may be implemented viaApplication Specific Integrated Circuits (ASICs), Field ProgrammableGate Arrays (FPGAs), digital signal processors (DSPs), or otherintegrated formats. However, those skilled in the art will recognizethat some aspects of the embodiments disclosed herein, in whole or inpart, can be equivalently implemented in integrated circuits, as one ormore computer programs running on one or more computers (e.g., as one ormore programs running on one or more computer systems), as one or moreprograms running on one or more processors (e.g., as one or moreprograms running on one or more microprocessors), as firmware, or asvirtually any combination thereof, and that designing the circuitryand/or writing the code for the software and or firmware would be wellwithin the skill of one of skill in the art in light of this disclosure.In addition, those skilled in the art will appreciate that themechanisms of the subject matter described herein are capable of beingdistributed as a program product in a variety of forms, and that anillustrative embodiment of the subject matter described herein appliesregardless of the particular type of signal bearing medium used toactually carry out the distribution. Examples of a signal bearing mediuminclude, but are not limited to, the following: a recordable type mediumsuch as a floppy disk, a hard disk drive, a CD, a DVD, a digital tape, acomputer memory, etc.; and a transmission type medium such as a digitaland/or an analog communication medium (e.g., a fiber optic cable, awaveguide, a wired communications link, a wireless communication link,etc.).

Those skilled in the art will recognize that it is common within the artto describe devices and/or processes in the fashion set forth herein,and thereafter use engineering practices to integrate such describeddevices and/or processes into data processing systems. That is, at leasta portion of the devices and/or processes described herein can beintegrated into a data processing system via a reasonable amount ofexperimentation. Those having skill in the art will recognize that atypical data processing system generally includes one or more of asystem unit housing, a video display device, a memory such as volatileand non-volatile memory, processors such as microprocessors and digitalsignal processors, computational entities such as operating systems,drivers, graphical user interfaces, and applications programs, one ormore interaction devices, such as a touch pad or screen, and/or controlsystems including feedback loops and control motors (e.g., feedback forsensing position and/or velocity; control motors for moving and/oradjusting components and/or quantities). A typical data processingsystem may be implemented utilizing any suitable commercially availablecomponents, such as those generally found in datacomputing/communication and/or network computing/communication systems.

The herein described subject matter sometimes illustrates differentcomponents contained within, or connected with, different othercomponents. It is to be understood that such depicted architectures aremerely exemplary, and that in fact many other architectures can beimplemented which achieve the same functionality. In a conceptual sense,any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality isachieved. Hence, any two components herein combined to achieve aparticular functionality can be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected”, or“operably coupled”, to each other to achieve the desired functionality,and any two components capable of being so associated can also be viewedas being “operably couplable”, to each other to achieve the desiredfunctionality. Specific examples of operably couplable include but arenot limited to physically mateable and/or physically interactingcomponents and/or wirelessly interactable and/or wirelessly interactingcomponents and/or logically interacting and/or logically interactablecomponents.

Each femtocell system can include the features of a computing device.FIG. 3 shows an example computing device 300 that is arranged foroperating with the systems described herein. Particularly, the computingdevice 300 illustrated can be configured as a femtocell system or beincluded in a femtocell system. Also, the various components of thecomputing device 300 can be included in the femtocell of FIG. 2. Thecomputing device 300 can be arranged with or operably coupled with anyof the components, network, and/or system in accordance with at leastsome embodiments described herein. In a very basic configuration 302,computing device 300 generally includes one or more processors 304 and asystem memory 306. A memory bus 308 may be used for communicatingbetween processor 304 and system memory 306.

Depending on the desired configuration, processor 304 may be of any typeincluding but not limited to a microprocessor (μP), a microcontroller(μC), a digital signal processor (DSP), or any combination thereof.Processor 304 may include one more levels of caching, such as a levelone cache 310 and a level two cache 312, a processor core 314, andregisters 316. An example processor core 314 may include an arithmeticlogic unit (ALU), a floating point unit (FPU), a digital signalprocessing core (DSP Core), or any combination thereof. An examplememory controller 318 may also be used with processor 304, or in someimplementations memory controller 318 may be an internal part ofprocessor 304.

Depending on the desired configuration, system memory 306 may be of anytype including but not limited to volatile memory (such as RAM),non-volatile memory (such as ROM, flash memory, etc.) or any combinationthereof. System memory 306 may include an operating system 320, one ormore applications 322, and program data 324. Application 322 may includea determination application 326 that is arranged to perform thefunctions as described herein. Program Data 324 may includedetermination information 328 that may be useful for analyzinginformation. In some embodiments, application 322 may be arranged tooperate with program data 324 on operating system 320 such that the workperformed by untrusted computing nodes can be verified as describedherein. This described basic configuration 302 is illustrated in FIG. 3by those components within the inner dashed line.

Computing device 300 may have additional features or functionality, andadditional interfaces to facilitate communications between basicconfiguration 302 and any required devices and interfaces. For example,a bus/interface controller 330 may be used to facilitate communicationsbetween basic configuration 302 and one or more data storage devices 332via a storage interface bus 334. Data storage devices 332 may beremovable storage devices 336, non-removable storage devices 338, or acombination thereof. Examples of removable storage and non-removablestorage devices include magnetic disk devices such as flexible diskdrives and hard-disk drives (HDD), optical disk drives such as compactdisk (CD) drives or digital versatile disk (DVD) drives, solid statedrives (SSD), and tape drives to name a few. Example computer storagemedia may include volatile and nonvolatile, removable and non-removablemedia implemented in any method or technology for storage ofinformation, such as computer readable instructions, data structures,program modules, or other data.

System memory 306, removable storage devices 336 and non-removablestorage devices 338 are examples of computer storage media. Computerstorage media includes, but is not limited to, RAM, ROM, EEPROM, flashmemory or other memory technology, CD-ROM, digital versatile disks (DVD)or other optical storage, magnetic cassettes, magnetic tape, magneticdisk storage or other magnetic storage devices, or any other mediumwhich may be used to store the desired information and which may beaccessed by computing device 300. Any such computer storage media may bepart of computing device 300.

Computing device 300 may also include an interface bus 340 forfacilitating communication from various interface devices (e.g., outputdevices 342, peripheral interfaces 344, and communication devices 346)to basic configuration 302 via bus/interface controller 330. Exampleoutput devices 342 include a graphics processing unit 348 and an audioprocessing unit 350, which may be configured to communicate to variousexternal devices such as a display or speakers via one or more A/V ports352. Example peripheral interfaces 344 include a serial interfacecontroller 354 or a parallel interface controller 356, which may beconfigured to communicate with external devices such as input devices(e.g., keyboard, mouse, pen, voice input device, touch input device,etc.) or other peripheral devices (e.g., printer, scanner, etc.) via oneor more I/O ports 358. An example communication device 346 includes anetwork controller 360, which may be arranged to facilitatecommunications with one or more other computing devices 362 over anetwork communication link (i.e., network 118) via one or morecommunication ports 364.

The network communication link may be one example of a communicationmedia. Communication media may generally be embodied by computerreadable instructions, data structures, program modules, or other datain a modulated data signal, such as a carrier wave or other transportmechanism, and may include any information delivery media. A “modulateddata signal” may be a signal that has one or more of its characteristicsset or changed in such a manner as to encode information in the signal.By way of example, and not limitation, communication media may includewired media such as a wired network or direct-wired connection, andwireless media such as acoustic, radio frequency (RF), microwave,infrared (IR) and other wireless media. The term computer readable mediaas used herein may include both storage media and communication media.

Computing device 300 may be implemented as a portion of a small-formfactor portable (or mobile) electronic device such as a cell phone, apersonal data assistant (PDA), a personal media player device, awireless web-watch device, a personal headset device, an applicationspecific device, or a hybrid device that include any of the abovefunctions. Computing device 300 may also be implemented as a personalcomputer including both laptop computer and non-laptop computerconfigurations.

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its spirit and scope, as will be apparentto those skilled in the art. Functionally equivalent methods andapparatuses within the scope of the disclosure, in addition to thoseenumerated herein, will be apparent to those skilled in the art from theforegoing descriptions. Such modifications and variations are intendedto fall within the scope of the appended claims. The present disclosureis to be limited only by the terms of the appended claims, along withthe full scope of equivalents to which such claims are entitled. It isalso to be understood that the terminology used herein is for thepurpose of describing particular embodiments only, and is not intendedto be limiting.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to embodiments containing only one suchrecitation, even when the same claaim 1ncludes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should be interpreted to mean “at least one”or “one or more”); the same holds true for the use of definite articlesused to introduce claim recitations. In addition, even if a specificnumber of an introduced claim recitation is explicitly recited, thoseskilled in the art will recognize that such recitation should beinterpreted to mean at least the recited number (e.g., the barerecitation of “two recitations,” without other modifiers, means at leasttwo recitations, or two or more recitations). Furthermore, in thoseinstances where a convention analogous to “at least one of A, B, and C,etc.” is used, in general such a construction is intended in the senseone having skill in the art would understand the convention (e.g., “asystem having at least one of A, B, and C” would include but not belimited to systems that have A alone, B alone, C alone, A and Btogether, A and C together, B and C together, and/or A, B, and Ctogether, etc.). In those instances where a convention analogous to “atleast one of A, B, or C, etc.” is used, in general such a constructionis intended in the sense one having skill in the art would understandthe convention (e.g., “a system having at least one of A, B, or C” wouldinclude but not be limited to systems that have A alone, B alone, Calone, A and B together, A and C together, B and C together, and/or A,B, and C together, etc.). It will be further understood by those withinthe art that virtually any disjunctive word and/or phrase presenting twoor more alternative terms, whether in the description, claims, ordrawings, should be understood to contemplate the possibilities ofincluding one of the terms, either of the terms, or both terms. Forexample, the phrase “A or B” will be understood to include thepossibilities of “A” or “B” or “A and B.”

In addition, where features or aspects of the disclosure are describedin terms of Markush groups, those skilled in the art will recognize thatthe disclosure is also thereby described in terms of any individualmember or subgroup of members of the Markush group.

As will be understood by one skilled in the art, for any and allpurposes, such as in terms of providing a written description, allranges disclosed herein also encompass any and all possible subrangesand combinations of subranges thereof. Any listed range can be easilyrecognized as sufficiently describing and enabling the same range beingbroken down into at least equal halves, thirds, quarters, fifths,tenths, etc. As a non-limiting example, each range discussed herein canbe readily broken down into a lower third, middle third and upper third,etc. As will also be understood by one skilled in the art all languagesuch as “up to,” “at least,” and the like include the number recited andrefer to ranges which can be subsequently broken down into subranges asdiscussed above. Finally, as will be understood by one skilled in theart, a range includes each individual member. Thus, for example, a grouphaving 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, agroup having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells,and so forth.

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting, with the true scope and spirit being indicated by thefollowing claims. All references recited herein are incorporated hereinby specific reference in their entirety.

The symbols used herein can be defined as follows: throughput T₀ ^(k);carrier wave k; carrier wave k1; carrier wave k2; fading matrix F;fading value between femtocells 0,i F_(0,I); interference correlativematrix D; predetermined threshold value Γ_(T); throughput incrementΔT_(i) of Femtocell_(i); i corresponds to one or more other femtocellsystems in a set I of the one or more other femtocell systems;interference I_(i) of femtocell_(i); interference I₀ of the firstfemtocell system; estimated channel quality γ_(i)′; channel qualityinformation □_(I); transmission power P₀ of the first femtocell system;P_(i) is transmission power of femtocelli; Ii is interference powerreceived by femtocell_(i); P_(i)′ is an estimation of the transmissionpower of femtocell_(i) by the first femtocell system; N is noise power;and |I₀| is the number of elements in the set I of the other femtocellsystems where fading value is less than the predetermined thresholdvalue Γ_(T).

The relationships provided herein include: If not T₀ ^(k)<Γ_(T) for k1then use second carrier wave k2; If T₀ ^(k)<Γ_(T) for k1 then use firstcarrier wave k1; If T₀ ^(k)>Σ_(iε1)ΔT_(i) then discard carrier wave k;and If not T₀ ^(k)>Σ_(iε1)ΔT_(i) then use carrier wave k.

The equations provided herein include:

$\begin{matrix}{T_{0}^{k} > {\sum\limits_{i \in I}^{\;}\;{\Delta\; T_{i}}}} & (1) \\{\gamma_{i} = {\frac{P_{i}}{I_{i} + N} \approx \frac{P_{i}^{\prime}}{I_{0} + N}}} & (2) \\{P_{i}^{\prime} \approx {\gamma_{i} \times \left( {I_{0} + N} \right)}} & (3) \\{\gamma_{i}^{\prime} = \frac{P_{i}}{I_{0} - \left( {P_{0} - F_{0,i}} \right) + N}} & (4) \\{\frac{\Delta\; T_{i}}{T_{i}} < {\frac{T_{0}^{k}}{T_{0} \times {I_{0}}}.}} & (5)\end{matrix}$

The invention claimed is:
 1. A method for distributed inter-cellinterference coordination in a communications system including at leasta first femtocell system and one or more other femtocell systems, themethod comprising: at one or more other femtocell systems, sendingchannel quality information γ_(i) of a subordinate device communicatingwith the one or more other femtocell systems to the first femtocellsystem; receiving the channel quality information γ_(i) of the one ormore other femtocell systems at the first femtocell system; estimatingan influence of a use of a resource on the communications system at thefirst femtocell system according to the channel quality informationγ_(i) received from the one or more other femtocell systems; anddetermining at the first femtocell system whether to use the resource.2. The method of claim 1, further comprising storing the channel qualityinformation γ_(i) of the one or more other femtocell systems at thefirst femtocell system.
 3. The method of claim 1, wherein sendingchannel quality information γ_(i) of a subordinate device comprisesbroadcasting the channel quality information γ_(i) of each carrier waveof the one or more other femtocell systems in a certain time period. 4.The method of claim 1, further comprising: obtaining a fading matrix Fat the first femtocell system of fading values between the firstfemtocell system and the one or more other femtocell systems; anddetermining an interference correlative matrix D at the first femtocellsystem corresponding to the fading matrix F relative to a predeterminedthreshold value Γ_(T).
 5. The method of claim 4, wherein estimating aninfluence of a use of a resource on the communications system comprisesestimating a throughput T₀ ^(k) of the first femtocell system which canbe obtained on a carrier wave k.
 6. The method of claim 5, whereinestimating an influence of a use of a resource on the communicationssystem further comprises: using the interference correlative matrix D toidentify a second femtocell system with strongest interference with thefirst femtocell system and a carrier wave k1 with the strongestinterference between the first femtocell system and the second femtocellsystem, wherein if not T₀ ^(k)<Γ_(T), where Γ_(T) corresponds to thepredetermined threshold value, the first femtocell system negotiateswith the second femtocell system about using a carrier wave k2, which isat least substantially orthogonal to the carrier wave k1, and wherein ifT₀ ^(k)<Γ_(T), the first femtocell system negotiates with the secondfemtocell system about using the carrier wave k1.
 7. The method of claim6, wherein estimating an influence of a use of a resource on thecommunications system further comprises determining which carrier wavesof the first femtocell system are being used by the first femtocellsystem.
 8. The method of claim 7, wherein estimating an influence of ause of a resource on the communications system further comprises: foreach of the carrier waves being used by the first femtocell system, thefirst femtocell system calculates the throughput T₀ ^(k) of the carrierwave k corresponding to what the decrement of the throughput will be onthe first femtocell system if the first femtocell system discards thecarrier wave k; and estimating an increment of throughput ΔT_(i) ofFemtocell_(i), after the first femtocell system discards the carrierwave k, where i corresponds to one or more other femtocell_(i) systemsin a set I of the one or more other femtocell systems where fading valueis less than the predetermined threshold value Γ_(T).
 9. The method ofclaim 8, wherein determining at the first femtocell system whether touse the resource comprises: discarding the carrier wave k at the firstfemtocell system if T₀ ^(k) and ΔT_(i) satisfy Equation (1):T ₀ ^(k)>Σ_(iεI) ΔT _(i); or  (1) continuing to use the carrier wave kif it T₀ ^(k) and ΔT_(i) do not satisfy the Equation (1).
 10. The methodof claim 8, wherein estimating an increment of throughput ΔT_(i) , offemtocell_(i), after the first femtocell system discards the carrierwave k comprises: approximating an interference I_(i) of each of theother femtocell_(i) systems in the set I as being equal to aninterference l₀ of the first femtocell system; and estimating channelquality γ_(i)′ using the channel quality information γ_(i) received atthe first femtocell system, a fading value F_(0,i) between the firstfemtocell system and each of the other femtocell_(i) systems in the setI, and a transmission power P₀ of the first femtocell system accordingto the following Equation (2), Equation (3), and Equation (4):$\begin{matrix}{\gamma_{i} = {\frac{P_{i}}{I_{i} + N} \approx \frac{P_{i}^{\prime}}{I_{0} + N}}} & (2) \\{P_{i}^{\prime} \approx {\gamma_{i} \times \left( {I_{0} + N} \right)}} & (3) \\{\gamma_{i}^{\prime} = \frac{P_{i}}{I_{0} - \left( {P_{0} - F_{0,i}} \right) + N}} & (4)\end{matrix}$ wherein P_(i) is transmission power of femtocell_(i),I_(i) is interference power received by femtocell_(i), P_(i)′ is anestimation of the transmission power of femtocell_(i) by the firstfemtocell system, N is noise power.
 11. The method of claim 8, whereinestimating an influence of a use of a resource on the communicationssystem further comprises: for each of the carrier waves not being usedby the first femtocell system, calculating the throughput T₀ ^(K) of thecarrier wave k corresponding to the increment of the throughput ΔT_(i)on the communication system when the first femtocell system uses thecarrier wave k; and estimating an increment of throughput ΔT_(i) offemtocell_(i), after the first femtocell system discards the carrierwave k, where i corresponds to each of the at least one other femtocellsystems in a set I of the other femtocell systems where fading value isless than the predetermined threshold value Γ_(T).
 12. The method ofclaim 9, wherein determining at the first femtocell system whether touse the resource comprises: using the carrier wave at the firstfemtocell system if T₀ ^(K) and ΔT_(i) satisfy Equation (5):$\begin{matrix}{\frac{\Delta\; T_{i}}{T_{i}} < \frac{T_{0}^{k}}{T_{0} \times {I_{0}}}} & (5)\end{matrix}$ where |I₀| is the number of elements in the set I of theother femtocell systems where fading value is less than thepredetermined threshold value; or not using the carrier wave k if T₀^(k) and ΔT_(i) do not satisfy the Equation (5).
 13. The method of claim12, wherein estimating an increment of throughput ΔT_(i) offemtocell_(i), after the first femtocell system discards the carrierwave k comprises: approximating an interference I_(i) of each of theother femtocell_(i) systems in the set I as being equal to aninterference I₀ of the first femtocell system; estimating channelquality γ_(i)′ using the channel quality information γi received at thefirst femtocell system, a fading status F_(0,i) between the firstfemtocell system and each of the other femtocell_(i) systems in the setI, and a transmission power P₀ of the first femtocell system accordingto Equation (2), Equation (3), and Equation (4): $\begin{matrix}{\gamma_{i} = {\frac{P_{i}}{I_{i} + N} \approx \frac{P_{i}^{\prime}}{I_{0} + N}}} & (2) \\{{P_{i}^{\prime} \approx {\gamma_{i} \times \left( {I_{0} + N} \right)}},} & (3) \\{\gamma_{i}^{\prime} = \frac{P_{i}}{I_{0} - \left( {P_{0} - F_{0,i}} \right) + N}} & (4)\end{matrix}$ wherein P_(i) is transmission power of femtocell_(i),I_(i) is interference power received by femtocell_(i), P_(i)′ is anestimation of the transmission power of femtocell_(i), by the firstfemtocell system, and N is noise power.
 14. A communications system fordistributed inter-cell interference coordination comprising: a firstfemtocell system; and one or more other femtocell systems configured tosend channel quality information γ_(i) of a subordinate devicecommunicating with the one or more other femtocell systems to the firstfemtocell system, wherein the first femtocell system is configured to:receive the channel quality information γ_(i) of the one or more otherfemtocell systems at the first femtocell system; estimate an influenceof a use of a resource on the communications system at the firstfemtocell system according to the channel quality information γ_(i)received from the one or more of the other femtocell systems; anddetermine at the first femtocell system whether to use the resource. 15.The communications system of claim 14, wherein the first femtocellsystem is further configured to store the channel quality informationγ_(i) of at least one of the other femtocell system.
 16. Thecommunications system of claim 14, wherein sending channel qualityinformation γ_(i) of a subordinate device comprises broadcasting thechannel quality information γ_(i) of each carrier wave of the one ormore other femtocell systems in a certain time period.
 17. Thecommunications system of claim 14, wherein the first femtocell system isfurther configured to: obtain a fading matrix F at the first femtocellsystem of fading values between the first femtocell system and the oneor more other femtocell systems; and determine an interferencecorrelative matrix D at the first femtocell system corresponding to thefading matrix F relative to a predetermined threshold value Γ_(T). 18.The communications system of claim 17, wherein estimating an influenceof a use of a resource on the communications system comprises estimatinga throughput T₀ ^(k) of the first femtocell system which can be obtainedon a carrier wave k.
 19. The communications system of claim 18, whereinestimating an influence of a use of a resource on the communicationssystem further comprises: using the interference correlative matrix D toidentify a second femtocell system with a strongest interference withthe first femtocell system and a carrier wave k1 with the strongestinterference between the first femtocell system and the second femtocellsystem, wherein if not T₀ ^(k)<Γ_(T), where Γ_(T) corresponds to thepredetermined threshold value, the first femtocell system negotiateswith the second femtocell system about using a carrier wave k2, which isat least substantially orthogonal to the carrier wave k1, and wherein ifT₀ ^(k)<Γ_(T), the first femtocell system negotiates with the secondfemtocell system about using the carrier wave k1.
 20. The communicationssystem of claim 19, wherein estimating an influence of a use of aresource on the communications system further comprises determiningwhich carrier waves of the first femtocell system are being used by thefirst femtocell system.
 21. The communications system of claim 20,wherein estimating an influence of a use of a resource on thecommunications system further comprises: for each of the carrier wavesbeing used by the first femtocell system, the first femtocell systemcalculates the throughput T₀ ^(k) of the carrier wave k corresponding towhat the decrement of the throughput will be on the first femtocellsystem if the first femtocell system discards the carrier wave k; andestimating an increment of the throughput ΔT_(i) of femtocell_(i), afterthe first femtocell system discards the carrier wave k, where icorresponds to each of the at least one other femtocell_(i), systems ina set I of the other femtocell systems where fading value is less thanthe predetermined threshold value Γ_(T).
 22. The communications systemof claim 21, wherein determining at the first femtocell system whetherto use the resource comprises: discarding the carrier wave k at thefirst femtocell system if T₀ ^(K) and ΔT_(i) satisfy Equation (1):T ₀ ^(k)>Σ_(iεI) ΔT _(i); or  (1) continuing to use the carrier wave kif T₀ ^(K) and ΔT_(i) do not satisfy Equation (1).
 23. Thecommunications system of claim 21, wherein estimating an increment ofthroughput ΔT_(i) of femtocell_(i), after the first femtocell systemdiscards the carrier wave comprises: approximating an interference I_(i)of each of the other femtocell_(i), systems in the set I as being equalto an interference I₀ of the first femtocell system; estimating channelquality γ_(i)′ using the channel quality information γ_(i) received atthe first femtocell system, a fading status F_(0,i) between the firstfemtocell system and each of the other femtocell_(i) systems in the setI, and a transmission power P₀ of the first femtocell system accordingto Equation (2), Equation (3), and Equation (4): $\begin{matrix}{\gamma_{i} = {\frac{P_{i}}{I_{i} + N} \approx \frac{P_{i}^{\prime}}{I_{0} + N}}} & (2) \\{P_{i}^{\prime} \approx {\gamma_{i} \times \left( {I_{0} + N} \right)}} & (3) \\{\gamma_{i}^{\prime} = \frac{P_{i}}{I_{0} - \left( {P_{0} - F_{0,i}} \right) + N}} & (4)\end{matrix}$ wherein P_(i) is transmission power of femtocell_(i),I_(i) is the interference power received by femtocell_(i), P_(i)′ is anestimation of the transmission power of femtocell_(i) by the firstfemtocell system, and N is noise power.
 24. The communications system ofclaim 21, wherein estimating an influence of a use of a resource on thecommunications system further comprises: for each of the carrier wavesnot being used by the first femtocell system, calculating the throughputT₀ ^(k) of the carrier wave k corresponding to the increment of thethroughput ΔT_(i) on the communication system when the first femtocellsystem uses the carrier wave k; and estimating an increment ofthroughput ΔT_(i) of femtocell_(i), after the first femtocell systemdiscards the carrier wave k, where i corresponds to each of the at leastone other femtocell systems in a set I of the other femtocell systemswhere fading value is less than the predetermined threshold value Γ_(T).25. The communications system of claim 22, wherein determining at thefirst femtocell system whether to use the resource comprises: using thecarrier wave k at the first femtocell system if T₀ ^(K) and ΔT_(i)satisfy Equation (5): $\begin{matrix}{\frac{\Delta\; T_{i}}{T_{i}} < \frac{T_{0}^{k}}{T_{0} \times {I_{0}}}} & (5)\end{matrix}$ where |I₀|is the number of elements in the set I of theother femtocell systems where fading value is less than thepredetermined threshold value; or not using the carrier wave k if T₀^(k) and ΔT_(i) do not satisfy Equation (5).
 26. The communicationssystem of claim 25, wherein estimating an increment of the throughputΔT_(i) of femtocell_(i), after the first femtocell system discards thecarrier wave k comprises: approximating an interference I_(i) of each ofthe other femtocell_(i) systems in the set I as being equal to aninterference I₀ of the first femtocell system; estimating channelquality Γ_(i)′ using the channel quality information γ_(i) received atthe first femtocell s_(y)stem, a fading status F_(0,i) between the firstfemtocell system and each of the at least one other femtocell_(i)systems in the set I, and a transmission power P₀ of the first femtocellsystem according to Equation (2), Equation (3), and Equation (4):$\begin{matrix}{\gamma_{i} = {\frac{P_{i}}{I_{i} + N} \approx \frac{P_{i}^{\prime}}{I_{0} + N}}} & (2) \\{{P_{i}^{\prime} \approx {\gamma_{i} \times \left( {I_{0} + N} \right)}},} & (3) \\{\gamma_{i}^{\prime} = \frac{P_{i}}{I_{0} - \left( {P_{0} - F_{0,i}} \right) + N}} & (4)\end{matrix}$ wherein P_(i) is transmission power of femtocell_(i),I_(i) is the interference power received by femtocell_(i), P_(i)′ is anestimation of the transmission power of femtocell_(i) by the firstfemtocell system, and N is noise power.
 27. A method for distributedinter-cell interference coordination in a first femtocell system, themethod comprising: receiving at the first femtocell system channelquality information γ_(i) of a subordinate device communicating with oneor more other femtocell systems interfering with the first femtocellsystem in a communications network; estimating at the first femtocellsystem an influence of a use of a resource on the communications systemaccording to the channel quality information γ_(i) received from the oneor more other femtocell systems; and determining at the first femtocellsystem whether to use the resource.
 28. The method of claim 27, furthercomprising storing the channel quality γ_(i) information of the one ormore other femtocell systems.
 29. The method of claim 27, whereinreceiving channel quality information γ_(i) of a subordinate devicecomprises receiving a broadcast of the channel quality information γ_(i)of each carrier wave k of the one or more other femtocell systems in acertain time period.
 30. The method of claim 27, further comprising:obtaining a fading matrix F at the first femtocell system of fadingvalues between the first femtocell system and the one or more otherfemtocell systems; and determining an interference correlative matrix Dat the first femtocell system corresponding to the fading matrix Frelative to a predetermined threshold value Γ_(T).
 31. The method ofclaim 30, wherein estimating an influence of a use of a resource on thecommunications system comprises estimating the throughput T₀ ^(k) of thefirst femtocell system which can be obtained on a carrier wave k. 32.The method of claim 31, wherein estimating an influence of a use of aresource on the communications system further comprises: using theinterference correlative matrix D to identify a second femtocell systemwith a strongest interference with the first femtocell system and acarrier wave k1 with the strongest interference between the firstfemtocell system and the second femtocell system, wherein if not T₀^(k)<Γ_(T), where Γ_(T) corresponds to the predetermined thresholdvalue, the first femtocell system negotiates with the second femtocellsystem about using a carrier wave k2, which is at least substantiallyorthogonal to the carrier wave k1, and wherein if T₀ ^(k)<Γ_(T), thefirst femtocell system negotiates with the second femtocell system aboutusing the carrier wave k1.
 33. The method of claim 32, whereinestimating an influence of a use of a resource on the communicationssystem further comprises determining which carrier waves of the firstfemtocell system are being used by the first femtocell system.
 34. Themethod of claim 33, wherein estimating an influence of a use of aresource on the communications system further comprises: for each of thecarrier waves being used by the first femtocell system, the firstfemtocell system calculates the throughput T₀ ^(k) of the carrier wave kcorresponding to what the decrement of the throughput will be on thefirst femtocell system if the first femtocell system discards thecarrier wave k; and estimating an increment of throughput ΔT_(i) offemtocell_(i), after the first femtocell system discards the carrierwave k, where i corresponds to each of the at least one otherfemtocell_(i) systems in a set I of the other femtocell systems wherefading value is less than the predetermined threshold value Γ_(T). 35.The method of claim 34, wherein determining whether to use the resourcecomprises: discarding the carrier wave k at the first femtocell systemif T₀ ^(K) and ΔT_(i) satisfy Equation (1):T ₀ ^(k)>Σ_(iεI) ΔT _(i); or  (1) continuing to use the carrier wave kif T₀ ^(k) and ΔT_(i) do not satisfy Equation (1).
 36. The method ofclaim 34, wherein estimating an increment of the throughput ΔT_(i) offemtocell_(i), after the first femtocell system discards the carrierwave comprises: approximating an interference I_(i) of each of the otherfemtocell_(i) systems in the set I as being equal to an interference I₀of the first femtocell system; estimating channel quality γ_(i)′ usingthe channel quality information γ_(i) received at the first femtocellsystem, a fading status F_(0,i) between the first femtocell system andeach of the other femtocell_(i), systems in the set I, and atransmission power P₀ of the first femtocell system according toEquation (2), Equation (3), and Equation (4): $\begin{matrix}{\gamma_{i} = {\frac{P_{i}}{I_{i} + N} \approx \frac{P_{i}^{\prime}}{I_{0} + N}}} & (2) \\{{P_{i}^{\prime} \approx {\gamma_{i} \times \left( {I_{0} + N} \right)}},} & (3) \\{\gamma_{i}^{\prime} = \frac{P_{i}}{I_{0} - \left( {P_{0} - F_{0,i}} \right) + N}} & (4)\end{matrix}$ wherein P_(i)is transmission power of femtocell_(i), I_(i)is the interference power received by femtocell_(i), P_(i)′ is anestimation of the transmission power of femtocell_(i) by the firstfemtocell system, and N is noise power.
 37. The method of claim 34,wherein estimating an influence of a use of a resource on thecommunications system further comprises: for each of the carrier wavesnot being used by the first femtocell system, calculating the throughputT₀ ^(k) of the carrier wave k corresponding to the increment of thethroughput ΔT_(i) on the communication system when the first femtocellsystem uses the carrier wave k; and estimating an increment ofthroughput ΔT_(i) of femtocell_(i), after the first femtocell systemdiscards the carrier wave k, where i corresponds to each of the at leastone other femtocell systems in a set I of the other femtocell systemswhere fading value is less than the predetermined threshold value Γ_(T).38. The method of claim 34, wherein determining whether to use theresource comprises: using the carrier wave k at the first femtocellsystem if T₀ ^(k) and ΔT_(i) satisfy Equation (5): $\begin{matrix}{\frac{\Delta\; T_{i}}{T_{i}} < \frac{T_{0}^{k}}{T_{0} \times {I_{0}}}} & (5)\end{matrix}$ where |I₀|is the number of elements in the set I of theother femtocell systems where fading value is less than thepredetermined threshold value Γ_(T); and not using the carrier wave k ifT₀ ^(k) and ΔT_(i) do not satisfy Equation (5).
 39. The method of claim38, wherein estimating an increment of throughput ΔT_(i) offemtocell_(i), after the first femtocell system discards the carrierwave comprises: approximating an interference Ii of each of the otherfemtocell_(i), systems in the set I as being equal to an interference I₀of the first femtocell system; estimating channel quality γ_(i)′ usingthe channel quality information γ_(i) received at the first femtocellsystem, a fading status F_(0,i) between the first femtocell system andeach of the other femtocell_(i) systems in the set I, and a transmissionpower P₀ of the first femtocell system according to Equation (2),Equation (3), and Equation (4): $\begin{matrix}{\gamma_{i} = {\frac{P_{i}}{I_{i} + N} \approx \frac{P_{i}^{\prime}}{I_{0} + N}}} & (2) \\{{P_{i}^{\prime} \approx {\gamma_{i} \times \left( {I_{0} + N} \right)}},} & (3) \\{\gamma_{i}^{\prime} = \frac{P_{i}}{I_{0} - \left( {P_{0} - F_{0,i}} \right) + N}} & (4)\end{matrix}$ wherein P_(i) is transmission power of femtocell_(i),I_(i) is the interference power received by femtocell_(i), P_(i)′ is anestimation of the transmission power of femtocell_(i) by the firstfemtocell system, and N is noise power.